Slowed Down
The past tense of "slow" is "slowed".
The past perfect tense of the word "slow" is "had slowed."
The past tense is sat down.
The past tense is stepped down.
The past tense is fell down.
The past tense of "slow" is "slowed".
The past perfect tense of the word "slow" is "had slowed."
The past tense is sat down.
The past tense is stepped down.
The past tense is fell down.
The past tense is downed.
The past tense of "lie down" is "lay down."
The past tense of "lay down" is "laid down."
The past tense of "lie down" is "lay down", and the past participle is "lain down".
past tense
The past participle of "slow down" is "slowed down."
Felled is the past tense of fell, which means to knock or cut down.